A press brake includes an upper table mounted with a punch and a lower table mounted with a die. The press brake lowers the upper table to the lower table, and bends a metal material in the state of being sandwiched between the punch and the die. In order to prevent that the hand of a person enters the area where the punch is lowered when the material is bent, the press brake includes a safety device which detects that an intrusion object such as the hand of a person enters the area and stops the operation of a bending processing.
As one of the safety devices, a so-called laser type of the safety device is provided which stops the operation of the bending processing when an intrusion object obstructs laser light. In this type of safety device, it is necessary not to stop the operation of the bending processing in a case where the laser light is obstructed by the bent material. Patent Literature 1 and 2 describes that a safety interval is set such that a finger does not enter the upper side of the material, and the safety device is invalidated after the punch reaches the area which is set in the safety interval above the material.